Defining Scales of Field Experiments to Assess Solar Radiation Modification, with Application to Marine Cloud Brightening Studies - Preprint

[Geoengineering News]

https://essopenarchive.org/doi/full/10.22541/essoar.175579033.31203983/v1

Authors

Sarah J. Doherty, Michael S Diamond, Robert Wood, Haruki Hirasawa

21 August 2025

Abstract

Solar radiation modification (SRM) is increasingly recommended for research by scientists and official bodies as a potential option for addressing climate risks while atmospheric greenhouse gas concentrations are reduced to safer levels. However, understanding about the potential efficacy, impacts, benefits and risks of different SRM approaches remains limited. Current knowledge almost exclusively stems from observation of natural analogues and from model simulations, with the former of limited direct applicability to SRM and the accuracy of the latter difficult to assess without testing against real-world observations. As such, it is generally acknowledged that well-designed field studies with controlled aerosol emissions would provide more robust assessment of SRM approaches. Herein we propose a framework for defining different scales of SRM field studies based on the studies’ spatial extent and duration, and the atmospheric energy perturbation they produce. We apply this framework to the proposed SRM intervention of marine cloud brightening (MCB), which would involve the targeted emission of sea salt to increase the reflectivity of oceanic clouds, and show how different scientific goals correspond to different study scales. A benefit of the proposed framework is that the study scales map well to existing analogues, which can thus provide observational estimates of the magnitude of physical impacts of different study scales and the detectability of different metrics of interest. While we focus primarily on this framing within the context of the physical science aspects of field studies, we note the utility of this framework in the context of the governance of such studies.

Source: ESS Open Archive